Circuit-closing thermostat



J. N. VANDEGRIFT. CIRCUIT CLOISING THERMOSTAT.

APPLICATION FILED FEB. 17, 1919.

1,348,338, Patented Aug. 3, 1920.

fig 4. 4g 15 w mo v UNITED STATES PATENT. OFFICE.

CIRCUIT-CLOSING THERMOSTAT.

Specification of Letters Patent.

Patented Aug. 3, 1920.

Application filed February 17, 1919. Serial m. 277,434..

To all whom it may concern:

Be it known that I, JAMES resident of Red Bank, county of Monmouth, andState of New Jersey, have invented certain new and useful Improvementsin Circuit-Closing Thermostats, of which the following is aspecification.

This invention relates generally to circuit closing thermostats, withmore particular reference to that type of device in which the melting ofa readily fusible alloy results in the deposit of the latter in suchplace and manner as to electrically connect the two wires of a normallyopen circuit. The device of my invention may doubtless serve many usefulpurposes, but I have especially in mind a thermal circuit closing devicefor employment in connection with automatic fire-alarm systems.

The principal objects of the present invention are, first, the provisionof a device which may be applied after installation of the wiring systemat any desired point, merely requiring removal of minor portions of theinsulation and without cutting the wires or the necessity of providingterminals or terminal binding posts; second, the provision of a devicewhich is exceedingly small in size and which may therefore be easilyconcealed and not impair the general sightliness of the decorations of aroom or chamber; third, the provision of a device which is practicallydust-proofit being well known that the accumulation of dust to a certaindegree prevents the establishment of electrlcal connection and thiswithout losing sight of the idea of simplicity of construction andapplication, and,'fourth, the utmost simplicit of constructioncompatible with dependa ility of operation and, therefore,inexpensiveness.

My invention will be more readily understood by reference to theaccompanying drawings, forming a part of this specification, in which- IFigure 1 is a side elevation of a practical and convenient embodiment ofthe invention;

Fig. 2 is a top plan view thereof;

Fig. 3 is a vertical section, taken substantially on the line 3-3 ofFig. 2;

Fig. 4 is a transverse vertical section, taken substantially on the lineof Fig. 1.

N. VANDE-' omr'r, a citizen of the United States, and a Fig. is a detailview of the two parts of the casing in unassembled condition;

F1 6 1s a view similar to Fig. 2 with the fusib e plug or disk and theouter retaining shell or cap removed.

Fig. 7 is a' view similar to Fig. 1 of a modified form of the device;

F g. 8 is a plan view of the same, and

Fig. 9 1s a transverse vertical section taken substantially on the line9--9 of Fig. 7

Referring now tothe drawings in detail, a and b designate the insulatedwires of an ordinary electric circuit, which may be one of any number ofsimilar circuits, from the same or different sources of electric energy,leading through various parts, sections or rooms of a building, andhaving the usual connections in a common annunciator or separateannunciators, suitably located, to simultaneously sound an alarm andindicate the location of trouble in the usual and well-known mannerunder conditions as hereinafter explained. It is to be understood thatthe circuit is normally open.

The circuit closing thermostat of my invention comprises a preferablycircular and slightly tapering sheet-metal shell 11 havingoppositely-disposed pairs of notches 12 and 13 in the lower edge or rimthereof adapted to receive and snugly contain the insulated wires aandb. I have shown a cup-shaped shell or bottom cap 14 adapted to betelescoped on the lower end of the shell 11 and close the same, theupper edge or rim of the shell 14 being provided with notches 12 and 13'which correspond with the notches 12 and 13 in the shell 11, wherebywhen the two parts 11 and 14 are assembled, as shown in the drawin s, athimble-shaped casing is provided whic is apertured for the passagetherethrough of the wires a and 6. Prior to the assembly of these partson the wires,

the insulation is cut from the latter for a distance slightly less thanthe diameter of the shell 11 at its lower end, whereby the edges of thenotches in the parts 11 and 14, when assembled. will engage theinsulation and not come in contact with the bare wires.

A disk, plug or cap 15, the same being formed from a more'or lessreadily fusible alloy, is adapted to fit snugly within the upper andlarger end of the shell 11. Alloys compounded for the purpose of fusionat comparatively low abnormal temperatures a e 1 911 kn n in this art tonecessitate detailed description here. Sufiice to say, for the purposesof this description, that upon the raising of the temperature in theimmediate vicinity of the device above what ma be termed the maximumnormal, this disk 15 will be melted and the molten fluid drop or flow tothe bottom of the chamber within the assembled parts 11 and 14, thusestablishing an electrical connection between the exposed wires thereinand closing the circ.uitwith result as herein-before set forth.

I have shown the cup-shaped bottom cap or shell 14 provided withupwardly-projecting and preferably integral arms 16 16 which extendabove the upper rim of the shell 11, whereby the extremities of saidarms may be bent over to engage the disk 15 and retain the same inplace. It will be apparent that these arms 16 16 serve the two-foldpurpose of retaining the disk 15 in place in the shell 11 and thesealing-cap 14 in place on the lower end ofsaid shell.

In Figs. 7, 8 and 9, I have shown the shell 11 provided with lugs 17 17projecting laterally from the lower edge or rim thereof,- and thesealing cup orshell 14' rovided with corresponding lugs 18 18 on theupper edge or rim thereof, the two parts being adapted to be securedtogether by small bolts 19 19 passing through the superposed lugswhereby the same are clamped together by means of the nuts 20 20. Inthis construction, I do not provide the cap of shell 14' with theupwardly-projecting arms, but form the shell 11' with lugs or ears 21 21on the upper edge or rim thereof, adapted to be bent over the disk 15'of fusible material to retain the same in place.

In use, after the wiring has been installed, and the locations for thethermostats having been selected, the insulation is cut from the wiresin the usual manner at these points, care being taken to expose thewires only throughout the desired distances, whereupon the shell 11 (or11') is first properly positioned, the disk 15 (or 15') having beenmounted therein, then the cap 14 (or 14') is assembledtherewith in themanner hereinbefore described, and either the ends of the arms 16 16 orthe lugs or cars 21 21-as the case may be-bent downwardly to engage saiddisk, whereupon the installationfor this articular station-is complete.

W ile I have referred to the wires a and 6 as providing a normally opencircuit, it

is well known that automatic fire-alarm systems. as a rule, include anordinary closed supervising circuit between battery terminals of whichone of these wires forms a part, the other wire connecting the firealarmgongs and annunciators, remaining a part of the circuit which isnormally open until said wire is connected with the firstmentioned wireby the fused alloy of the thermostat.

Many modifications of minor details of my improved circuit closingthermostat will doubtless readily suggest themselves to those skilled inthe art to which it appertains, and I therefore do not desire to limitmy invention to the specific construction herein shown and described.

I claim:

1. In a device of the character described, the combination of acup-shaped receptacle through which the insulated wires of an electriccir'cuit'are adapted to be passed with a minor portion'of the insulationon each wire within said receptacle removed, and a body of readilyfusible metallic material mounted and retained above the de-insulatedportions of said wires.

2. In a device of the character described, the combination of twoseparable members assembled to form a cup-shaped apertured shell throughthe lower part of which the insulated wires of an electric circuit areadapted to be passed with a minor portion of the insulation on each wirewithin said shell removed, and abody of readily fusible metallicmaterial mounted and retained in said shell above the de-insulatedportions of said wires. n

3. In a device of the character described, the combination of twoseparable and interfitting members assembled in telescopic arrangementto form a cup-shaped apertured shell through the lower part of which theinsulated wires of an electric circuit are adapted to be passed with aminor portion of the insulation on each wire within said shell removed,and a body of readily fusible metallic materialmounted and retained insaid shell above the de-insulated portions of said wires.

4. In a device of the character described, the combination of twoseparable members assembled to form a cup-shaped apertured shell throughthe lower part of which the insulated wires of an electric circuit areadapted to be passed with a minor portion of the insulation on each wirewithin said shell removed, and a body of readily fusible metallicmaterial in said shell above the de-insulated portions of said wires,one of said members being provided with means for removably retainingsaid body in place.

5. In a device of the character described, the combination of twoseparable members assembled to form a cup-shaped apertured shell throughthe lower part of which the insulated wires of an electric circuit areadapted to be passed with a minor portion ofthe insulation on each wirewithin said shell removed, a body of readily fusible metallic materialmounted and retained in said shell above the de-insulated portions ofsaid wires, and means for detachably secursaid members together inassembled con- 1 ion.

6. In a device of the character described, the combination of twoseparable members assembled, to form a cup-shaped apertured.

shell through the lower part of which the insulated wires of an electriccircuit are adapted to be passed with a minor portion of the insulationon each wire within said shell removed, a body of readily fusiblemetallic material in said shell above the de-insulated portions of saidwires, and means which at the same time secures said members together inassembled condition and retains said body in place.

7. In a device of the character described, the combination of an annularshell, a cupshaped shell having telescopic connection therewith to closeone end thereof, the edges of said elements being provided withregistering notches adapted to form wire-containing apertures when saidelements are assembled, a disk of readily fusible metallic materialfitting within the open end of said annular shell, and means on saidcup-shaped shell for retaining said disk in place.

8. In a device of the character described, the combination of an annularshell, a cupshaped shell having telescopic connection therewith to closeone end thereof, the edges of saidelements being provided withregistering notches adapted to form wire-containing apertures when saidelements are assembled, and a disk of readily fusible metallic materialfitting within the open end of said annular shell, said cup-shaped shellbeing provided with arms projecting above the upper edge of said annularshell and adapted to be bent over said edge to retain said disk in placeand said shells in assembled condition.

9. In a device of the character described, the combination, withcontiguously arranged insulated wires of an electric circuit, of acup-shaped receptacle through which said wires pass and within which aminor portion of the insulation has been removed from each wire, and abody of readily fusible metallic material mounted and retained above thede-insulated portions of said wires.

10. In a device of the character described, the combination, with thecontiguouslyarranged insulated wires of an electric circuit,

of two members assembled to form a cupshaped apertured shell through thelower part of which said wires pass and within which a minor portion ofthe insulation has been removed from each wire, and a body of readilyfusible metallic material mounted in said shell above the de-insulatedportions of said wires.

In testimony of the foregoing, I have hereunto set my hand in thepresence of two witnesses.

' JAMES N. VANDEGRIFT. Witnesses:

ELEANOR C. KELLY, FRED H. BOWERSOCK.

